PHPePub not loaded

Can't get ePub generated. PHPePub is installed in "sites/all/libraries" and print settings page recognizes it's place at "sites/all/libraries/PHPePub/src/PHPePub/Core". But :
- I get a white screen on my content page (the one to print epub) and
- as well my status page is white also,
- with this error in my logs:
PHP Fatal error: Class 'EPub' not found in /path-to-drupal/sites/all/modules/print/print_epub/lib_handlers/print_epub_phpepub/print_epub_phpepub.module on line 52
and
Fatal error: Class 'EPub' not found in /home/athan/domains/info-grece.com/public_html/info-grece/sites/all/modules/print/print_epub/lib_handlers/print_epub_phpepub/print_epub_phpepub.pages.inc on line 31
I think this is a problem with namespaces of PHPePub defined in PHPePub/src/PHPePub/Core/EPub.php

namespace PHPePub\Core;

use com\grandt\BinStringStatic;
use DOMDocument;
use PHPePub\Core\Structure\Ncx;
use PHPePub\Core\Structure\NCX\NavPoint;
use PHPePub\Core\Structure\Opf;
use PHPePub\Core\Structure\OPF\DublinCore;
use PHPePub\Core\Structure\OPF\MarcCode;
use PHPePub\Core\Structure\OPF\MetaValue;
use PHPePub\Core\Structure\OPF\Reference;
use PHPePub\Helpers\FileHelper;
use PHPePub\Helpers\ImageHelper;
use PHPePub\Helpers\StringHelper;
use PHPePub\Helpers\URLHelper;
use PHPZip\Zip\File\Zip;
use RelativePath;

If I define "namespace PHPePub\Core" at the top of "print_epub_phpepub.module" and "print_epub_phpepub.pages", then on my content page when clicking on the "Epub version" link
- something seems to work but it stops with a redirection to "mysite.com/{node_nid}" and ends with a "page not found",
- print settings page reports that I have no epub generation tool selected
- status report is no more white but says the same "No EPUB tool selected"